[请教]BIOS地址映射?

暴雪

原512K的ROM，现换了一个1M的ROM，windows下在 0xFFF0 0000~0xFFF7 FFFF 可以看到追加的512K的内容。
但在启动计算机时(BIOS没有初始化计算机），无法访问追加的512K的ROM。
0 ]! @5 {% _4 v3 t(可以访问原512K的ROM 0xFFF8 0000~0xFFFF FFFF)

. U9 X5 O. g' E% N9 E我的计算机用的是intel的ICH7南桥。
在手册上
FWH_SEL2—Firmware Hub Select 2 Register (LPC I/F—D31:F0)
: N. i0 ^1 e( a1 K0 sFWH_70_IDSEL — R/W. IDSEL for two, 1-M Firmware Hub memory ranges.
! I/ R" q! N9 O0 ~' x- d3 x. ^The IDSEL programmed in this field addresses the following memory ranges:
2 F2 q" I+ }- X$ L5 W4 R- z" DFF70 0000h – FF7F FFFFh
FF30 0000h – FF3F FFFFh
( P  |  ^3 P. a8 b$ @8 E在这里 IDSEL 如何理解。
FWH_DEC_EN1—Firmware Hub Decode Enable Register
(LPC I/F—D31:F0)
- E4 w! G3 B# ~+ Q7 J- Y+ W% LFWH_70_EN — R/W. Enables decoding two 1-M Firmware Hub memory ranges.
0 = Disable.
. ]( o8 j, ^5 s1 = Enable the following ranges for the Firmware Hub
0 c1 j0 W+ \! P- C( Y& cFF70 0000h – FF7F FFFFh
1 K3 r* H, N' b: ?3 A  A( P8 T6 YFF30 0000h – FF3F FFFFh
除了上面的数据区域，还有其它的数据区域控制ROM到内存地址的映射吗？
. I/ X4 ]+ l, m/ [, |
谢谢大家了！！！

xtdumpling

IDSEL是LPC spec的一个信号(Device Select),
This one clock field is used to indicate which of multiple Firmware components is being selected.
The four bits transmitted over AD[3:0] during this clock are compared with values strapped onto
pins on the Firmware component. If there is a match, the Firmware component will continue to
decode the cycle to determine which bytes are requested on a read or which bytes to update on a
write. If there isn’t a match, the Firmware component may discard the rest of the cycle and go into
a standby power state.

详见LPC spec:
http://www.intel.com/design/chipsets/industry/25128901.pdf
0 a% U9 s4 q# D) ?3 R
在ICH 7 中似乎就这几个吧(FWH_SEL1,FWH_SEL2,FWH_DEC_EN1,BIOS_CNTL),据我现在知道的.